Pressure loaded pump



D. s. OLIVER 2,866,416

PRESSURE LOADED PUMP Original Filed June 16, 1950 Dec. 30, 1958 5 Sheets-Sheet 1 def Oliver Dec. 30, 1958 2,866,416

D. S. OLIVER PRESSURE LOADED PUMP 5 Sheets-Sheet 2 Original Filed June 16, 1950 afar:

UZzIz/er amj6fm Dec. 30, 1958 oLlvER 2,866,416

PRESSURE LOADED PUMP Original Filed June 16, 1950 5 Sheets-Sheet 3 A WW g fil-ili is Ill 1223.70.74 I

Dec. 30, 1958 s, OLIVER 2,866,416

PRESSURE LOADED PUMP Original Filed June 16, 1950 5 Sheets-Sheet 4 Dec. 30, 1958 D, s, OLIVER 4 2,866,416

PRESSURE LOADED PUMP fnz/enir peler'i' 5 Oliver" close limits the actual sealing pressure provided.

2,866,416 PRESSURE LOADED PUMP Delbert S. Oliver, Euclid, Ohio, assignor to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Original application June 16, 1950, Serial No. 168,622,

new Patent No. 2,756,681, dated July 31, 1956. Divided and this application September 27, 1955, Serial No. 540,970

19 Claims. (Cl. 103-126) This is a division of application Serial Number 168,622, filed by Delbert S. Oliver on June 16, 1950, now Patent No. 2,756,681, entitled Pressure Loaded Pump."

This invention relates to a gear pump, and more particularly to a gear pump of the type employing pressure loaded bushings, such gear pumps sometimes being referred to as pressure loaded gear pumps.

in a pressure loaded gear pump of the type having one set of axially movable pressure loadable bushings, a part of the output pressure is applied to the rear or motive surfaces of the axially adjustable bushings to urge these bushings into sealing engagement with their associated gears. As disclosed in U. S. Patent No. 2,420,622 to Roth et al., by carefully selecting the relative areas of the forward surfaces of the bushings and of the motive surfaces of the bushings, it is possible to control within very In practice, this requires a somewhat higher effective pressure in the direction of seal than in the direction tending to open the seal.

in the usual form of pressure loaded pump, the pressure loading motive chamber to which output pressure is supplied will be substantially uniformly subjected to the output pressure. That is to say, at any point on the motive surfaces at the rear of the bushing, the same pressure will exist. This is not true of the forward or gear side face engaging surface of the bushing. This forward surface is normally subjected to a distinct pressure gradient extending from the inlet pressure in the area adjacent the pump inlet, which is the lowest pressure of the gradient, to the outlet pressure in the area adjacent the discharge side of the pump, at which area the pressure gradient is at its highest level. Accordingly, it will be evident that while the total pressure forces acting on the motive surfaces of the bushing may be made to equal the total pressure forces acting on the forward surfaces of the bushing, or to exceed these latter forces, the pressures acting on particular areas of the forward surfaces will not be uniform and the portion of the forward bushing surface nearer the inlet will be subjected to a lesser pressure tending to break the seal than the portion of the forward bushing surface nearer the outlet of the pump. This unbalanced pressure condition tends to twist the bushing in the pump and results in uneven wear, thereby increasing the power required to turn the pump. Wear is, of course, concentrated on the inlet side of the pump.

It has been found that this unbalanced condition can to some extent be reduced by providing balancing grooves in the gear side face engaging surfaces of the pressure responsive bushings, these balancing grooves communicating at one end with the discharge side of the pump and extending coaxially of the bushings toward the inlet port of the pump, but terminating short thereof. The balancing grooves tend'to render the pressure uniform over a larger area of the gear surface than without the grooves. It will be evident, however, that it is not possible to extend the balancing grooves completely around the pump without providing a leakage path to the inlet side of the pump nited States Patent from the outlet side with consequent loss of pressure. Thus, while balancing grooves are helpful, they do not result in a perfectly balanced pump.

It has also been proposed to employ eccentrically disposed bushings whereby the pressure area at the back of the bushings is offset withrespect to the uniformly disposed surface at the forward surface of the bushings so as to compensate, in effect, for the pressure gradient extending across the forward surfaces of the bushings. This is disclosed and claimed in Haberland application Serial No. 130,904, filed December 3, 1949, now Patent No. 2,823,615. Alternatively, it has been proposed to restrict the area exposed to loading pressure at the back of the bushings. This is disclosed and claimed in the Compton application, Serial No. 163,011, filed May 19, 1950, now Patent No. 2,824,522. The present invention is directed to various seal arrangements for restricting the loading area at the back of the pressure loadable bushings to compensate for the pressure gradient across the forward surfaces of the bushings.

An object of the present invention is to provide a new and improved pressure loaded type, intermeshing gear pump.

A further object of the present invention is to provide a pressure loaded type, intermeshing gear pump wherein the motive surface areas of the pressure loadable bushings are controlled to establish a loading force having an effective gradient substantially equivalent to the pressure gradient across the forward surfaces of the loadable bushings.

In accordance with one embodiment of this invention, a pressure loaded type, intermeshing gear pump having one set of axially movable, pressure loadable bushings, may be provided with sealing means disposed across the motive surface areas of the bushings in such manner as to restrict or confine the high pressure area, so that the pressure loading area occupies a preselected fraction of the total surface area and so that this preselected area is so located as to establish a loading force matching substantially the pressure gradient across the forward or gear side face engaging surfaces of the bushings. By suitably locating the sealing means, a proper balance can be reached whereby the gradient of the forces tending to hold the bushing against the gear side face is closely balanced and uniformly disposed with respect to the gradient of the forces tending to move the bearing away from the gear side faces, that is, to unload the pump.

Other objects and advantages of the present invention will be apparent from the following detailed description taken in conjunction with the drawings wherein:

Fig. 1 is a fragmentary, axial, sectional view of a pressure loaded type, intermeshing gear pump in which the pressure loading areas of one set of bushings are restricted in accordance with one embodiment of this invention;

Fig. 2 is a transverse, sectional view taken substantially along the line 2-2 of Fig. 1;

Fig. 3 is a detail, sectional view taken along the line 33 of Fig. 2;

Fig. 4 is a detail, perspective view of a suitable seal retaining plate;

, Fig. 5 is a fragmentary, sectional view similar to Fig. 2 showing, however, the pressure loading surfaces of a bushing provided with a seal arrangement in accordance with a second embodiment of this invention, the view being taken substantially along the line 55 of Fig. 6;

Fig. 6 is a sectional view taken along the line 6-6 of Fig. 5;

Fig. 7 is a fragmentary, axial, sectional view, similar to Fig. 1, showing, however, a third sealing arrangement in accordance with this invention, the view being taken substantially along the line 7-7 of Fig. 8;

Fig. 8 is a transverse, sectional view taken substantially along the line 8-8 of Fig. 7;

Fig. 9 is a view similar to Fig. 7 showing, however, a fourthernbodiment of this invention employing a diiferent type of seal arrangement, the view being taken substantially along the line 9-9 of Fig. 10;

Fig. 10 is a sectional view taken substantially along the line 10-10 of Fig. 9.;

Fig. 11 is an enlarged, detail, sectional view taken substantially along the line 11-11 of Fig. 10;

Fig. 12 is a fragmentary view similar to Fig. 9 showing a fifth embodiment of this invention, the view being taken substantially along the line 12-12 of Fig. 13;

Fig. 13 is asectional view of the fifth embodiment of this invention taken substantially along the line 13-13 of Fig. 12; V

Fig. 14 is a sectional view similar to Fig. 9 showing, however, a sixth embodiment of this invention, the view being taken substantially along-theline 14-14 of .Fig. 15;

Fig. '15 is a sectional view taken substantially along the line 15-15 of Fig. 14 showing the sixth embodiment of this invention;

Fig. 16 is-a view similar to Fig. 12 showing, however, a seventh embodiment of this invention, the view'being taken substantially along the line 16-16 of Fig. 17;

Fig. 17 is a sectional view taken along .theline 17-17 of Fig. 16 showing this seventh embodiment of this :invention;

Fig. 18 is a view partially in section taken along the line 18-18 of Fig. 17;

Fig. 19-is a'view similarto Fig. 18 showing, however, a blade type seal in place of the pin type seal of Fig. 18;

Fig. '20 is..'a view-similar to Fig. 2 showing, :however, a .modification thereof permitting -the pump to-be operated in either direction; and

Fig. -21 shows various cross-sectional configurations which may be employed for the seal, particularly in' the embodiment shown in-Fig. 20.

Referring .now to the drawings, and particularly to Figs. 1, 2 :and 3 thereof, a pump similar to that shown inthe aforementioned Roth et al. patent, except for the bushing loading arrangement, is there illustrated having a sectional housing comprising a main body portion and .a right closure member 21. These sections are securely bolted together and-cooperate to define therewithin a pair of parallel axes,intersecting bores or pumping gear chambers22'and 23 which are arranged-to receive in complementary relationship intermeshing pumping gears .24 and 25 respectively. In .the embodiment illustrated, the pumping gears have integrally formed therewith-hollow journal shafts 26 and 2.7, .respectively, and the leftportions of the journal shafts .26 and 27 are received in conventional flanged bushings 30 and 31 mounted in the left. portion of the pumping ,gearchambers 22"an'd 23. The right portions .o f-the gear journals 26 and '27 arereceived, respectively, in axially-adjustable, pressure loadable, flanged bushings 32 and 33 mounted in the right side of the pumping .gear chambers 22-and 23. The bushings 32\and 33 are provided with .specially designed sealing means inaccordance with the present invention and this'will be described in detail hereinafter. In the embodiment illustrated the upperpumpinggear 24 is'the driving gear and is rotated "in a clockwise direction, as viewed in Fig. 2. In accordance with conventiona'lpump design practice, thej'journal shaft '26 of the gear 24 may be extended to the'left,-as viewed in Fig. 1, and coupled to a suitable power source. Low pressure liquid "is introduced into the pump'housing at inlet-'34, formed in the left side of the pump housing as viewed in Fig. 2, and high pressure liquid is discharged through outlet 35, formed in the right side ofthe housing, as viewed in Fig. 2, the inlet and outlet sides communicating with theinlet and discharge 'areas of the rntermeshing pumping gears. The pressure loadable bushings 32 and 33 are fitted intothe bores 2'2'an d 23 with sufiicient clearance to permit slight axial movement of the bushings with respect to the bores.

In the operation of a pump of this type, discharge pressure generated by the intermcshing gears may be communicated from the outlet or discharge side thereof to the annular pressure loading areas at the back of the bushings, designated 32-11 and 33-a in the drawings, through an axially extending passage 36 formed between the peripheries of the flanged portions of the bushings on the discharge side of the pump at the point of convergence of the flanged portions of the bushings. The passage 36 extends from the discharge side of the gears to the right, as viewed in Fig. 1, to the intercommunicating portions of the pressure loading areas at their point of juncture. Escape of discharge pressure rearwardly from the pressure loading surfaces is substantially prevented by means of an O-ring seal 37 disposed about the periphery of therear or barrel portion of each bushing in an annular groove 38 formed in portions of the the periphery o'f'the bushing. Alternatively, the groove 38 may be formed in the housing bore wall and an O- 'ring'37 then of slightly greater size would be positioned in the groove in the housing wall and engage at its inner periphery the periphery 'of the barrel portion of each bushing. Pressure leaking past the O-ring seal may be vented to inlet pressure or'to a zone of intermediate pressureinaccordance with conventional pressure loaded pump practice as set forth'in the above referenced Roth et alpatent.

In the operation of a gear pump of the type herein shown, a pressure gradient existsacross the facesof the bushings adjacent the 'gears, the pressure gradient extending from a low pressure value corresponding to the inlet pressure of the pump on the inlet side thereof to a pressure value corresponding to the discharge pressure of the pump at the 'outletsi-de thereof. On the other hand, the pressure applied to the motive surfaces 32-41 and 33-a is normally'substantially'uniform over the full extent thereof. It will be apparent, therefore, that since the gear side face pressure acting against the loading pressure in the area adjacent the discharge side of the pump exceeds the-gear side face pressure acting against the loading pressure in the area adjacent the inlet side of the pump, the axially movable bushings 32 and 33 will tend to engage the gear side faces with a correspondingly greater force adjacent the inlet side. This unbalanced arrangement results in increased wear and more particularly uneven wear, resulting in accelerated deterioration of the pump. The present invention is designed to overcome this unbalanced condition.

In accordance with the first embodiment of this invention, three elongated seals 40, 41 and 42 of U-shaped cross-section are-employed to-restrict the area at the back of the bushings exposed to loading pressure. These seals may be formed of neoprene, rubber or other'suitable resilient-material. Seal 41 is -"disposedbetween the barrel upper 'and lower bushings, substantially along the vertical center line of the pump, as viewed in Fig.2, with the open or lip portion'of theseal facing toward the right, and its 'innerside laying against the flanged portions of the'bushings. The terminal'ends of the seal touchin sealingrelation-the adjacent'barrel'portions. Seal 40is positionedso that its lower end touches the upper side of the barrel portionof bushing 32'and its upper end touches the inner wall of the housing bore,'tl1e lip portion'also facing to .the right. The seal is thus disposed'radially of the bushing barrel and, while shown in 'Fig. 2 as aligned with 'thevertical center line of the pump, may be located to the right'or to the left thereof to increase "or to reduce the area lying to the right of the seal whichis exposed to discharge pressure. Seal 42 is located "against the'fianged portion of thelower side of'the bushing in complementary location to the seal 40, 'the'seal 42 having its upper end touching the barrel o'f 'bushing 33 and'itslower 'endtlre inner'side wall of bore 23. The lip portions of all seals face to the right as viewed in Fig. 2. In order to prevent the seals from being moved to the left in response to application of discharge pressure, semi-annular retainer plates 43 and 44, respectively, are associated with the upper and lower bushings, the plates 43 and 44 being disposed against the left sides. of the flanged portions of the bushings, that is, against the left surfaces 32a and 33-a as viewed in Fig. 2 and supporting at their ends the left sides of the seals. The retainer plates 43 are made slightly smaller in axial thickness than the normal spacing between the right end of the flanged portion of each bushing and the adjacent end of the bore in which the bushing is positioned so that the seals, which are made somewhat thicker so that an initial seal is provided, may be placed under slight compression even in the absence of loading pressure being applied to the seals.

In the operation of the pump in accordance with the invention disclosed in Figs. 1, 2, 3 and 4, loading pressure is communicated to the loading areas of the bushings through the passage 36. This causes expansion of the lip portions of the seals thereby preventing escape of pressure to the left, as viewed in Fig. 2, and thus restricting the pressure loading area in accordance with the disposition of seals 40 and 42. Pressure leaking past the seals to the left, as viewed in Fig. 2, may be vented to inlet pressure through a passage 45, similar to passage 36, but formed on the opposite side of the bushings at their point of convergence.

It will be apparent from the foregoing that by selecting the location particularly of seals 40 and 42 it is possible to closely control the actual area on the back of each bushing exposed to discharge pressure. By preventing application of discharge pressure to a portion of the area at the back of the bushings adjacent the inlet side of the pump, the pressure gradient may, therefore, be closely compensated. Annular recesses 46 and 47 formed in the forward surfaces of each of the bushings radially inwardly of the gear teeth may be vented to inlet pressure in accordance with usual pressure loaded pump practice, as set forth in the aforementioned Roth et al. patent, to control the extent of the area exposed to discharge pressure at the forward surfaces of the bushings. Where the seals 49, 41 and 42 are employed, however, it is not ordinarily necessary to employ the vented recesses 46 and 47.

As pointed out in the co-pending application of John A. Lauck, Serial No. 168,587, filed June 16, 1950, now Patent No. 2,745,356, these recessed areas may be offset to compensate for the pressure gradient, and this feature may be employed, of course, in combination with the various embodiments of the present invention disclosed herein.

Referring now to Figs. 5 and 6, a second embodiment of this invention is there illustrated which avoids the use of the retaining plates 43 and 44. In accordance with this embodiment of the present invention, the flanged portions of each of the bushings are provided with grooves in which are received sealing pins whereby the area exposed to discharge pressure is limited, the pins functioning similarly to the seals 40, 41 and 42.

More particularly, a groove 51 is formed in the upper side portion of the rear or pressure loadable surface of the flanged part of upper bushing 32, the groove extending radially from the barrel portion of the bushing to the periphery of the flanged portion. Preferably, the groove has a V-shaped cross-section, as shown in Fig. 6. As with the seal 40 and the seal 42, the groove 51 may be located either to the right or to the left of the vertical center line of the pump to increase or reduce the area exposed to loading pressure. A groove 52 is formed at the lower side of the flanged portion, the groove extending from the barrel of the bushing and formed in the flange and extending to the periphery of the flange at the point of juncture thereof with the adjacent flanged portion of the lower bushing where it is in communication and alignment with a third groove 53 similarly formed in the upper side of the flanged portion of the lower bushing. Grooves 52 and 53 are preferably formed along the vertical center line of the bushings, but this may also be varied without departing from the present invention. A single pin 54 is positioned in the grooves 52 and 53 and a further pin, not shown, is positioned in a groove corresponding to groove 51 but formed in the lower side of the flanged portion of the lower bushing. The seal pins may be made either of metal or of a resilient material such as rubber or neoprene. Where the pins are made of metal, it is preferable that the pins be under no initial compression in the absence of loading pressure. That is to say, that when the bushings are assembled in the pump housing there must be suflicient clearance between the back of the housing bore and the flanged portion of the bushing, and more particularly of the grooves 51, 52 and 53 so that the pins are free to move from right to left therein. Thus, upon application of discharge pressure from passage 36, the metal pins are, in effect, rolled to the left in a wedging action to establish a seal between the back of the housing bore and the flange of each bushing.

On the other hand, where rubber pins are employed, it has been found in practice that it is desirable that there be slight initial compression of the rubber pins upon assembly of the bushings in the housing. In the absence of such initial compression, extrusion of the rubber pins may occur upon application of high discharge pressure. The operation of the rubber pins in response to discharge pressure is slightly different than that of the metal pin in that the rubber will change shape in response to the application of pressure tending to fill the left side of the grooves, as viewed in Fig. 5, although the pins will tend to roll somewhat also.

While this embodiment of the invention has been described in connection with V-shaped grooves, grooves having a curved cross-section can also be employed, although this latter configuration ordinarily involves an increase in manufacturing cost.

Referring now to Figs. 7 and 8, a third embodiment of the present invention is there illustrated wherein blade type seals are employed. This embodiment of the invention requires a modification of the housing bore on the right side thereof comprising making the right portion of the housing bore the same in diameter as the mid-pertion, rather than being reduced as shown in Fig. 1. In the embodiment shown in Figs. 1 to 4 and the embodiment shown in Figs. 5 and 6, no modification of the housing bore over the standard pressure loaded pump housing bore configuration disclosed in the Roth et al. patent is required. However, in the present embodiment, conventional flanged bushings similar to those described in conjunction with Figs. 1 to 4 are employed and the same reference numerals have been used todesignate corresponding parts.

As with the two previously described embodiments of the present invention, in this embodiment of the invention three seals are employed in conjunction with the flanged bushings, these seals being designated 60, 61 and 62 in Fig. 8 and having, as may be seen best in Fig. '7, a generally rectangular configuration. The location and arrangement of these seals on the back of the flanged portions of the bushings is substantially identical to that of the various seals described in accordance with previous embodiments. However, because the blade type seals extend axially to the rear of the flange portions of the bushings a substantially greater amount than the U-type seal shown, for example, in Figs. 1, 2, 3 and 4, a special supporting or retainer arrangement is employed in accordance with the present embodiment comprising two pairs of half rings, the upper set of rings being designated 63 and the lower set 64. These rings are utilized in a manner similar to the retainer plate 43 shown in Fig. 4 but because operation in either direction is provided in this pumping gear.

embodiment and in order :to provide .albetter support for the seal blades, instead of having only one half ring .as- *sociated with each bushing, a pair ofrings are employed.

The terminal ends, that is, the adjacent ends of each .of the half rings of atpairiare, of .course, slightly :spaced to receive .therebetween one of the seal blades.

Referring particularly to Fig.7, it'will be seen :that Ithe rings have a generally rectangular cross:sectional .confignration but that the upper .half ring .63 has integrally formed therewith la downwardly protruding shoulder 63-.a at its left lower side, the lower edge of which shoulder bears 'against the barrel portion of the upper side of the bushing in sealing relation, and an upwardly extending shouldered portion 63-'b, the upper edge of which bears against the-bore side wall in sealing relation,

and .a r'ightwardly protruding portion 63-c which bears against the end wall or cover 69 of the housing. Rings .64 are similarly constructed. The annular passages provided by this shouldered ring -'confi-g-uration permit -'discharge pressure-to be appliedto-the sealing blades. A pair of semi-annular, washer-type springs .65 are associated witheach pair of half rings, being positioned at the left ends thereof, as viewed in Fig. 7. These springs .163 and 64-c load the blades against the bushings to provide an initial loading pressure on the bushings :against the gear side faces and at the same time cause contact of'the half rings and the cover 69 to provide a seal. Circular washer-type springs 66 positioned at the right end of each bushing and loaded within the protruding portion 63-c and 64-0 load the blades against the bushings. A large -O-ring seal 67 is carried in a groove formed in the cover 69 which surrounds both bushings as shown.

Depending on the direction of operation of the pump, discharge pressure will be applied to the blades attheir side faces either from-the passage 56 or from the passage 45. This embodiment, 'as will 'be readily apparent .to those skilled in the art, permits of considerable savings in construction in view of-the'simplification of the cover 69. At the same time the center distance of the pump body bores is lesscritical and sincethe bushings locate in the body bores only, misalignment is substantially completely avoided. The seal afforded by the half rings makes unnecessary the provision of the'usual O-ring seals about the barrel portions of the bushings.

Referring now to Figs. 9, and 11, a'fourth embodiment of this invention is there illustrated wherein a twopiece bushing assembly is employed in conjunction with sealing blades to effect a restriction of the area exposed to loading pressure. In these drawings, the upper and lower bushing assemblies are designated 70 and 71, respectively, and are identical in construction. The housing bore construction and configuration is substantially the same as that illustrated in conjunction with Figs. 1 through 4.

Referring now particularly to Fig. '9, it will be seen that the upper bushing assembly 70 comprises an annular bushing member 72 having an inwardly flanged ring portion 73 formed at its forward surface and the inwardly flanged portion is made to have an inner diameter such that it engages'closely the journal portion of the associated A tubular or barrel portion 74 of the bushing assembly 70 fits around the journal portion of the pumping gear and its left portion is received within the body portion of the front member 72, the left end of the barrel butting against .the right side wall of the flange 73. In order to hold the bushing member 72 against the gearside facein initial sealing relation, a coiled spring '75 is positioned between the right end of the barrel portion 74.-and the inner side of the cover 21. A similararrangementis employedin'conjunction with the 'lower bushing assembly. The use of the two-piece bushing assembly facilitates the formation'of the slots, best shown in Figs. 10 and 11 to receive the sealing outwardly against the cover.

,8 :blades. .As shown in Fig. .11, a first rectangularly shaped :slot 761is formed in .the .bushingmember 72 of the .bushling assembly, theslot extending from .the right side, as viewed .in Fig. 9, .towar'dthe leftor gear .side face engaging surface .so that the open .end of :the .slot .is disposed .at .the back .of :the bushing member. A second .slot .77 similar to that shown in Fig. .11 is formed in the upper .side of .the :bushing member associated with the lower bushing assembly. These .two slots are aligned to receive a single blade seal 78. A .thirdislot .is formed in the upperside of the .uppercover member, and a fourth slot :81 in :the lowerside of the lower cover member, and .these lattertwo slots may .be located to the right or to the left of the vertical center line of the bushings, as viewed in.Fig. 1.0, 'to increase or reduce the area exposed to pressure. While a single blade 78 may be used with the :two communicating .slots 76 and 77 formed at the junction of the two bushings, separate blades 82 and'83 are :provided in the upper and lower slots 80 and 81, respectively.

In .order to .provide .an initial seal, a leaf type spring 64 is positioned between the upper ends of each blade and the .end .wall of the-associated slot in which it is .positioned, as shown'in Fig. 11. This assures an initial contact. Immediately .upon application of discharge pressurethrough the passage 85 formed at the convergence .of .the two flanged or cover members 70 and 71, pressure will be effective to force the exposed lower end, as viewed iiuFig. 1 l, of the blade to the left by pivoting it slightly about the l'ower left corner of the slot which causes the upper right edge of the blade to engage the right side wallof the'slot and, because the spring 84 urges the blade downward, as-viewed in Fig. 11, the lower right Icornerof the blade/is held inengagement with the cover. In practice this has been found .to'provide a very satisfactory seal. By varying the location of the slot and the positions ofthe blades,'the area exposed to discharge pressure may be closely controlled. Any pressure leaking past the seal may be 'vented to inlet pressure through passage 86, corresponding to passage 45 in Fig. 2. It also will be apparent that in the event higher than normal inlet pressure is used with the pump, then inet pressure 'will be effective on the area lying to the left of the sealing blades, as viewed in Fig. 10. The advantages of so utilizing inlet pressure are described in detail in the application of James A. Compton, Serial No. 163,012, filed May 19, 1950, now Patent No. 2,695,566.

Referring now to Figs. 12 and 13, a fifth embodiment of this invention-is illustrated wherein the sealing means for restricting the area to which discharge pressure is applied at the back of the bushings consists of springloaded pistons.

In thisembodiment of the invention no modification of the housing or bores is required over that shown in Fig. l, but a bushing having a somewhat thicker flange, viewed in an axial direction as in Fig. l2, is preferably employed since the flanged portion of the bushing is pro- 'vided with cylindrical recesses 91 and 92 extending from its back surface to a point adjacent its forward surface to receive the piston-type seals 93 and 94. Alternatively, of course, the seals may be contained in bores or apertures formed in the cover instead of in the bushings, this involving a modification of the housing. Springs 95 are associated'w'ith each of the pistons and urge them The peripheries of the piston must fit closely the barrel and housing side walls to provide the required seal. The springs 95'avoid the use of loading springs such as shown in Fig. -9. 'However, it is desirable to employ O-ringseals 95*about the barrel portions of the bushings behind the piston'seals, as illustrated. By locating the piston seals in'accordancewith the principles of'the previously described embodiments of this invention,'it will be apparent that the surface exposed to inlet pressure and 'the surface exposed to discharge pressure at the back of each of the axially movable bushings may be closely controlled to compensate for the pressure.gradient. across the gearsidefacer engaging surfaceof the bushings;

ReferringnowtoE-igs. 14.,and15; asixth embodiment of; this..inyention;is-. there illustrated wherein a unitary seal. of' somewhat! figure rlike configuration. is. em? ployed. torestrietithe; pressureloading. area. at the back of theaxially movablebushings. This... arrangement has the advantage of not: requiring; anyrmodification of :either the bushingstor ofithe housing bore. The .sealicomprises two. circular sections 14H: and 1il2iwhich. are disposed aroundfiheharrelzportionl of; the upper. and lower bushings, respectively, and. are; joined: by a. straight. portion HE -lying along thetvertical center; lineof; the. pumpbetween the two barrels, as.vie.wedzin-.Eig. 15; A. rod-like extension llldis integrally. formed. withtheseal atthe upper sideo-f the upper circulanportion 101 and extends radially; thereof whilea similar-rod-likeportion 195 extendsldownwardly radially from.the lower edge of the lowerportion of the ring: seal; The sealzmay be made ofrubber, neoprene, or-other. similar suitable material.

In order to prevent distortion. of: the sealiunder high dischargepressure, flat, half. ring retainer: plates 1.86, 187, 18.8 and 1tt9are empIoyedLand'are disposedaround theseal in suchmanner. as to. support. particularly the upwardly extending. portion and the downwardly ex.- tending. portion aswell asthe central joining portion. These half: ring plates may. be similar to .'the plate 43 shown in.Fig. 4.. The upwardly. extending portion 104 and. the downwardly extending portion 105- may, of course, bemoved totheright or. the left of. the vertical center line to-increase orreduce-the area exposedto discharge .pressure. At the same time inlet pressure is ap-. plied to-the remainingareaat the, back of thebushing. This type of sealarrangernent has the further advantage of making. unnecessary. the use of an O-ring seal betweenthe-barrel:portionofthe bushing and the adjacent housing, asshown particularly in.Fig. 1 andFig. 12, for example. It will be appreciated thatthe seal must be under initial compression upon assembly. of the bushings in the pump housing so that immediately. upon application of dischargepressure to theseal, the seal w-illbe pressed outwardlyto establisheda leakrproof seal. The plates 106, 107, 108 and 109;may, be, made either of metal or plastic material and;must, of course, besligh'tly thinner in an axial direction than the seal so as not to cause mechanical compression against thebushings when the bushings are initially assembled in the pump housing. By counterboring the b ack ofthe flanged; portions of the bushings to providerecesses inwhich-the seal would; be positioned, it is possible ,toavoiduse. of the supporting retainer plates. However, this expedient, while practical, is-

somewhat more expensive involving as it does, several additional manufacturing operations.

Referring now to Figs. 16. 17 and 18, a seventh embodiment of this invention is there illustrated wherein a twopiece bushing assembly is employed together with pin-type sealing means, similar to those discussed in connection with the embodimentof the invention illustrated in Figs. and 6. Because of the .two -pie ce bushing assembly construction the housing bore isnot reduced in thearea adjacent the barrel portion of the flanged bushing so that.

the housing bore in theembodiment shown in Figs. 16, 17 and 18 is generally similar to that shown in Figs. 7 and 8, that is .to say, the bore or chamberin which the pump gearsand in which theflanged portion of the bushing is;

upper pressure loadable bushing ofthe pump, together.

withering, member 111,which is disposed around the barrel portion ofthe bushing-110 .and hasprovided there-.

on .at its outer, rearedge a .re arwardlyextendin'g annular fiange lll which engages the left side of the cover. An

Q i ssss 3v i p ed.=. etwee heperip e y f. t

barrel portion of the bushing and the ring member 111 -1L,the;0-ring-seal being. received in a recess. 114% formed in the. periphery, ofthe barrel portion. Alternativelygthe ringseal might be positioned in. anannular, groove formed in; the-inner periphery; of, the ring. member 111".v

Referring now to Figs. 17 and 18, it-willbe seenzthat a groove l-l5 isformed in the upper side of-the ring mem:-v her 111 on, the; face thereof adjacent therear. of the flanged surfaceofi the; bushing andthe. groove extends radially-outwardly; from theinner to the. outer periphery of the.- ring; member. A second groove 1-16:is.formed; in the ring member on the same face thereof? 35511116 first groove; but positioned: on th e opposite; side-ofi the barrel portion of the bushing, and this .slot isaligned -with-athird groove 117-forrriedina seeondringmember 118 associ: atedwith the. lowerbushing; assembly. A fourth groove (not shown) is formed in the lower side of the ring memher 118, the lower bushing assembly being substantially identical in construction with the upper bushing assembly; In the upper. groove 115 -is positioned a pin seal l20 which maybe made either of metal. or a resilient material-and which, ifresilient, is placedunderslight compression upon assembly-of, the. bushing in the. pump housing. A similar pinIseal.lzlispositionedzin the two alignedgrooves 116 and.1-17, and,a.third;p in seal (not. shown) is positioned in the fourth groove. The grooves may be, V--shaped in.

crossesectional configuration .or. curved.

Upon. application. of discharge pressure through pas sage 3,6.thepinseals are compressedagainst the left sides.

of the. grooves andestablish therequisite seal between theringmembersandthe flanged rear surface of :thebushings. Thepimseals ancLgrooves. may, of .course, be located to: the.-right .or to theleft-of. the.center,line as with'the other embodiments. of the invention. This embodiment. p0s-- sesses theadvantagescf coversimplificationdescribed in conjunction, with Figs...7 and.8and'may also..be operated in either directiom The initialclearancebetween therings. and the adjacent flanged surfaces must, .of course, be critically selected with reference, to .thesealmeans :to prevent extrusion.

In Fig. 19 a modification ofthev sealing arrangement shown in Fig. 18 is illustrated. Deep slots..123 similar-to. theslots shown in conjunction with Eigs. 9,.10.and 11,are provided, the slots,being ..formed. in thering member 118:

on the sidethereofladjacent the flanged portionv ofthe.

bushing rathenthan in thebaclcof the ring -member,.as in Figs. 9, 10 and 11; These slots correspond to the relatively shallowgroovesinwhich the pin seals of. Figs. 16, 17and 18 are positioned. In these slots. are positioned blades 124 and between the back of each slot and the associated blade is positioned a leaf spring.125.or other suitable resilient means to urge the, blade into sealing.

-' Fig 11 and'the same'considerations as to angular..dis-.

position apply.

The embodiment shown in Fig. ZO'is illustrative, ofa modification of thepresent invention whichis applicable to each of the previously described embodiments. With. theexception of the particular arrangement shown.in Figs. 1 through 4, each ofthe embodiments ofjthisinvenr; tion described willoperate equally well incither direction of rotation of the pumping gears insofar. as.,the. provision ofa seal to restrict the pressure loadingarea.

is concerned. Of course, if the pressure loading area-is made larger than the area exposed to or vented .to inlet pressure or a zone of low pressure, ,then the. pump; will.

not work equally well in either direction. That ,is to say,

that in ordertor. thepumps vto workequally well in either, directionlhe: pressureloading area must be the same. for. either, direction of, rotation of the pumpingproviding amaddit-ionahseal. means. at ;the upper side. of i the flanged portion and. an :additional. seal means at the 11 lower side of the flanged portion to provide two alternative loading areas. The centrally disposed seal is located as with the previously described embodiments, but referring to the'upper bushing, in Fig. 20, a first, radially extending seal 126 disposed against the flanged portion is located to the left of the vertical centerline of the bushings and a second radially extending seal 127 is located to the right of the vertical center line, both seals being located at the upper portion of the bushing. Between these seals is positioned an arcuate retainer plate 128 generally similar to the plate 43 shown in Fig. 4 except that it is much shorter. Arcuate retainer plate 129 positioned between the left seal 126 and the central seal 130 corresponds in function to the seal 43 of Fig. 4. Arcuate retainer plate 131 positioned between the right seal 127 and the central seal 130 prevents movement of the seal 127 and-the seal 130 when discharge pressure is applied through the passage 45 rather than the passage 36. A similar arrangement is employed with the lower bushing. It will be understood that whether the seal be a pin seal or a blade seal, or a bushing assembly be employed withthe supporting rings as, for example, shown in Fig. 8, the principle of balanced loading areas disclosed 'in this embodiment is equally applicable. By increasing or by reducing the angular spacing between the seals 126 and 127 and correspondingly increasing or reducing the length of the retainer plate 128, the areas exposed to loading pressure and the areas vented to low pressure may be varied as to both size and location and will be equal for either direction of operation so long as symmetry of disposition of the seals is maintained. Because the lip type seal shown in Fig. 4 works best when pressure is applied to the lip from the right, as viewed in Fig. 2, the pin type or blade type seals are usually preferable'when the modification shown in Fig. 20 is employed in conjunction with any of the previously described embodiments.

The embodiment illustrated in Fig. 20 also permits controlling the area exposed to inlet pressure independently of the area exposed to discharge pressure within considerable limits.

In Fig. 21 various cross-sectional configurations have been illustrated which may be employed for the pin type seals, particularly those used in conjunction with pumps for operation in either direction. The seal pin 133 is of circular configuration while the seal pin 134 is of rectangular configuration. The seal ring 135 is indented on either side so that the configuration is that of opposed Vs. The cross-sectional configuration of the pin seal 136 is similar in character to that of 135 except that rather than V-shaped notches the seal is longitudinally grooved to define more or less rectangular cross-sectioned grooves, thus providing a pair of spaced lips on either side of the body portion. These seal configurations are merely illustrative and any suitable seal may. be employed.

Where herein the various parts of this invention have been referred to as being located in a right or a left position, or an upper or a lower position, it will be understood that this is done solely for the purpose of facilitating description and that such references relate only to the relative positions of the parts as shown in the accompanying drawings.

What is claimed is:

1. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, means defining an end plate facing away from said rotatable member, sealing means radially disposed on said end plate second surface area effective to divide said area into a plurality of segments isolated from each other, passage defining means effective to direct pressure liquid generated by said rotatable member to one segment of said second surface area when said rotatable member is rotated in one direction, passage defining means effective to direct pressure liquid generated by said rotatable member to another of said segments of said second surface when said rotatable member is rotated in the opposite direction, and means for preventing substantial angular movement of said sealing means irrespective of the direction of rotation of said rotatable member.

2. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, means defining an axially adjustable end plate received in said pump chamber and having a first surface area subject to the pressures in said pump chamber and engageable with the adjacent side face of said rotatable member to provide a pumping seal therewith, a second surface area on said end plate facing away from said rotatable member, sealing means radially disposed on said end plate second surface area effective to divide said area into a plurality of segments, isolated from each other, passage defining means effective to direct pressure liquid generated by said rotatable member to one segment of said second surface area when said rotatable member is rotated in one direction, and passage defining means effective to direct pressure liquidgenerated by said rotatable member to another of said segments of said second surface when said rotatable member is rotated in the opposite direction.

3. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, means defining an axially adjustable end plate received in said pump chamber and having a first surface area subject to the pressures in said pump chamber and engageable with the adjacent side face of said rotatable member to provide a pumping seal therewith, a second surface area on said end plate facing away from said rotatable member, sealing means radially disposed on said end plate second surface area effective to divide said area into a plurality of segments, isolated from each other, passage defining means eflective to direct pressure liquid generated by said rotatable member to one segment of said second surface area when said rotatable member is rotated in one direction, passage defining means effective to direct pressure liquid generated by said rotatable member to another of said segments of said second surface when said rotatable member is rotated in the opposite direction, and means for preventing substantial angular movement of said sealing means irrespective of the direction of rotation of said rotatable member, one of said passage defining means being effective to communicate inlet pressure to the associated segment of said surface when the other of said passage defining means is effective to direct pressure generated by the rotatable member to another seg ment of said surface. t

4. In a pressure loadable bushing for a pressure loaded type gear pump, said, bushing having a flanged forward portion adapted to engage at its forward surface the side surface of, a pumping gear in sealing relation and a tubular journal portion extending rearwardly from. said flanged portion, sealing means for restricting the area of the rear surface of said flanged portion exposed to loading pressure, said sealing means comprising a plurality of rod-like members extending radially from said bar- 13 rel portion and lying flatly against said flanged portion, said bushing having grooves formed therein to receive said rod-like elements.

5. In a pressure loadable bushing for a pressure loaded type gear pump, said bushing having a flanged forward portion adapted to engage at its forward surface the side surface of a pumping gear in sealing relation and a tubular journal portion extending rearwardly from said flanged portion, sealing means for restricting the area of the rear surface of said flanged portion exposed to loading pressure, said sealing means comprising a plurality of rod-like members extending radially from said barrel portion and lying flatly against said flanged portion, said bushing having grooves formed therein to receive said rod-like elements, said grooves having a V-shaped crosssection whereby angular movement of said members with respect to said flanged portion causes said members to tend to move out of said grooves.

6. A pressure loadable bushing for a pressure loaded type pump, said bushing having an annular forward sur' face adapted to engage at its forward surface the side surface of a pumping gear in sealing relation in response to loading pressure applied to the rear surface of the bushing, and sealing means for restricting the area of the rear surface of said bushing exposed to loading pressure, said sealing means comprising a plurality of blade-like members of generally rectangular cross-section, segmental ring-like retainer members for preventing movement of said blades, and resilient means for holding said blades in sealing relation.

7. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable element received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, a pressure loadable bushing having a flanged forward portion adapted to engage at its forward surface a side surface of said rotatable element in sealing relation in response to fluid pressure being applied to the rear surface of said flanged portion, said rear surface being spaced from the adjacent end wall of said pump chamber, blade-like sealing means disposed in radial array on said bushing rear surface, retainer means for preventing angular displacement of said blade sealing means and resilient means for holding said sealing means in sealing position.

8. In a pressure loadable bushing assembly for a pressure loadable type gear pump, said bushing assembly comprising an annular forward portion adapted to engage at its forward surface the side surface of a pumping gear in sealing relation and a rearwardly extending tubular journal portion, sealing means for restricting the area of the rear surface of said annular portion exposed to loading pressure, said sealing means comprising a plurality of blades disposed in radially extending slots formed in the back surface of said annular member.

9. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber,

means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an axially adjustable bushing assembly received in said pump chamber and comprising an annular forward member adaptedto l i urging said blades against the end wall of said housing to maintain a sealing relation.

10. In a pressure loadable bushing for a pressure loaded type gear pump, said bushing having a flanged portion adapted to engage at its forward surface the side surface of a pumping gear in sealing relation in response to the application of discharge pressure to the rear surface of the flanged portion, sealing means for restricting the area of the rear surface of said flanged portion exposed to loading pressure, said sealing means comprising a plurality of piston-like members received in recesses formed in the rear surface of said flanged portion, and resilient means for maintaining said piston-like members in sealing relation.

11. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an annular bushing received in said pump chamber and adapted to engage at its forward surface the adjacent side surface of said rotatable member in pumping seal relation in response to application of discharge pressure to the rear surface of said bushing, sealing means for restricting the area of the rear surface of said bushing exposed to loading pressure, said sealing means comprising a plurality of piston-like members received in recesses formed in the rear surface of said bushing and extending axially with respect to said pumping member, and resilient means associated with said piston-like members for urging said piston-like members against the adjacent end wall of said pump chamber to maintain a sealing relation.

12. A fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chamber, means including a rotatable member received in said pump chamber effective to force fluid from said inlet out of said housing through said outlet, an annular bushing received in said pump chamber and adapted to engage at its forward surface the adjacent side surface of said rotatable member in pumping seal relation in response to application of discharge pressure to the rear surface of said bushing, said bushing having a rear-wardly extending tubular portion received in said pump chamber, sealing means for restricting the area of the rear surface of said annular bushing exposed to loading pressure, said sealing means comprising a plurality of piston-like members of cylindrical configuration received in recesses formed in the rear surface of said bushing and extending axially with respect to said pumping member, said piston-like members bearing against in sealing relation the radially outer side of said tubular portion at their inner side surfaces and at their radially outer side surfaces bearing against the inner side wall of said pump chamber, and resilient means associated with said piston-like members for urging said piston-like member ends against the adjacent end wall of said pump chamber to maintain a sealing relation.

13. In a pressure loadable bushing for a pressure loaded type gear pump, said bushing having an annular forward portion adapted to engage at its forward surface the side surface of a pumping gear in sealing relation in response to the application of discharge pressure to the .rear surface of said bushing and said bushing having a tubular journal portion extending rearwardly from said flanged portion, sealing means for restricting the area of the rear surface of said flanged portion exposed to loading pressure comprising a generally circular sealing member of resilient material disposed about said tubular portion and having one side surface in contact with said annular portion rear surface, said sealing member having angularly spaced, radially extending, finger-like portions disposed against the rear surface of said flanged portion in sealing relation.

14. A fluid pump comprising ,a housing having ,apair of parallel axes -pump chambers ,foririe'dWheiein', "said housing having an inlet leading 'to and an outlet leading from said pump chambers, a pairof intermeshingpumping gears,dispos,ed,in.s aid pump chamber and effective'to ,force fluid froml saidinletoutof ,said housirig through said outletpbushin' means for Qsaid u-rnping-gears in cluding a pair of axially movable, ,pressure" lo adable bushings received in {Said p nip, Chambers and I adapted to engage'at theirforwardsurfaees the adjacent side surfaces ofsaid. ppm'ping ge" ,1r-s'' infpurriping seal relation in response to applieation 'ofi discharge pressure to the rear surfaces of said bushings, said pressureloadable bushings ,having flangedforwardportions and tubular rearwardly extending I portions, Qa nd sealing means forrestricting the area ofth'e rear. surfaces of said bushings exposed to'load- ,ing" pressure,"said lsealing means compris g ,a generally cirwlar se n m mb d spo e 21191 h tubal jp'qrtion of each bushing, andhavingoneside 's urfagefincont c wit t flanged ert enf e li f c v fiaserrl seal member disposed against the ,rear surfacesfofsaid flanged portionsin sealing relationar djoni'g the two circular I members, and at lea-st one o ther fingerilike seal 7 member associated with each of "said 1ci rcular ,rnembers and x nd n r di l autward th r aa i s fi rar surface of v the associated flanged' pdrtibn'ftddefine ,with said firstfinger like member a segmental pressure loading area at the rear. surface of said flanged portion.

15. A two-piece bushing ga ssembly "for a pressure-loadable type pump comprising a flanged member adapted to engage afgear side face at its forwardisurface'insealing relation and'having a tubular; r ear war'dlyextendin'g por tion and an annular member'adaptedto embrace the-tnbular portion of the'first member irisubstantiallytelescopic relation, said; flanged member being adapted to engage at its forward surface a' gear side face'in sealing relation in response to application of pressure tothe surface of said flanged member adjacent said annular member, and radially disposed sealing means located between-the rear surface of said flanged portion and the forwardsur'face 'of said annular member to divide the annular pressure'loading surface into at least two isolated areas. i

16. A two-piece bushing assembly for a pressure loadable typepump comprising a flanged member adapted to engage a gear side'face at its forward surface in sealing relation and having a tubular, rearwardly extending portion and an annular member adapted toembr ace "the tubular portion of the first member in substantially te lescopic relation, said flanged member being adapted tto engage at its forward surface a gear side face in sealing relation in response to application of pressure to the surface of said flangedmember adjacent ,said annular member, and radially disposed. sealingmeans located between the rearsurface of said flanged portion andlthe forward surface of said annular member to divi'deithe annular pressure loading surface into atlleast two isolated areas, one of said two adjacent surfaces associated .With said sealing means having a plurality of grooves .formed therein to receive said sealing means. i I I V 17. A twopiece bushing assembly fora pressure loadabletype pump, comprising a flanged memberadapted to engage a gear side;faceatitsforwardsurfaceinsealing relation and having a. tubular, rearwardly. extending portion and. van. annular member. adapted. to 1 embrace the 16 tubular p'ortion of the first member insubstantially-teles'copic relation, said flanged member being adapted to ,engage at its forward surface a gear side face in sealing're- 'lation in response toapplication of pressure to the surface of said flanged member adjacent said annular member, and radiallydisposed sealing means located between the rearsurface of said flanged portion and the forward portion and an annular member adapted toembrace the tubular portion of-the firstmernber in substantially telescopic relation, said flanged member being adapted to engage at its forward surface a gear side facein sealing relation in response to application of pres'sure'to the surface of said flanged member adjacent said annular member, and radially disposed sealin'gmeans located between the rearsurface of said'flanged portion and the "forward surface'of said annular member -to divide the annular pressure loading surface into at least two isolated areas, one of said two adjacent surfaces associated with said-sealing means having a plurality of grooves formed therein to receivesaid sealingmeans, said sealing means comprisingblades of generally rectangular configuration partially received in said grooves, and resilient means for urging said blades into sealing relation.

-19.' A -fluid pump comprising a housing having a pump chamber formed therein, said housing having an inlet leading to and an outlet leading from said pump chainber, means including a rotatable member received in'said pump chamber effective to force fluidfrom said inlet out ofsaid-housingthrough said outlet, means defining an axially adjustable end plate received in said pump chamber andhaving a first surface area subject to the pressures in said pump chamber and engageable with the adjacent side face of said-rotatable member to provide a pumping seal therewith, a second surface areaonsaid "end plate facing away from said rotatabletmember, sealing means radiallydisposedon saidend plate.second surface area effectivet'o dividesaidarea. into three segmental areasisolatedfromeach other, .passage defining means effectivetodirect pressure.liquidgeneratediby said rotatable .member to' av firstsegmental area whensaid .rotatable member is rotated in tone direction,, and.pa's- .sage .definmgmeans .effective to .direct ,pressure liquid generated by said rotatable ,membentoa second and oppositely .disposed segmental area. when. said rotatable .member is rotated .invthewopposite direction.

References Cited in the file ofthispatent UNITED STATES PATENTS 46 5;907 Whipple Dec. .29, 1891 2,044.,873 Beust June 23, 1936 2,312,655 Lauck Marf2, 1 943 2,312,891 Ferris Mar. 2 1943 "2,420,622 Roth et a1. Q 'May 13,1947

2,472,031 'Wich0rek L -May 31, 1949 7 2,527,941 Lauck et al Oct.- 31, 1-950 

